Modern Instrumental Limits of Identification of Ignitable Liquids in Forensic Fire Debris Analysis

Forensic fire debris analysis is an important part of fire investigation, and gas chromatography– mass spectrometry (GC-MS) is the accepted standard for detection of ignitable liquids in fire debris. While GC-MS is the dominant technique, comprehensive two-dimensional gas chromatography–mass spectrometry (GC GC-MS) is gaining popularity. Despite the broad use of these techniques, their sensitivities are poorly characterized for petroleum-based ignitable liquids. Accordingly, we explored the limit of identification (LOI) using the protocols currently applied in accredited forensic labs for two 75% evaporated gasolines and a 25% evaporated diesel as both neat samples and in the presence of interfering pyrolysate typical of fire debris. GC-MSD (mass selective detector (MS)), GC-TOF (time-of-flight (MS)), and GC GC-TOF were evaluated under matched conditions to determine the volume of ignitable liquid required on-column for correct identification by three experienced forensic examiners performing chromatographic interpretation in accordance with ASTM E1618-14. GC-MSD provided LOIs of ~0.6 pL on-column for both neat gasolines, and ~12.5 pL on-column for neat diesel. In the presence of pyrolysate, the gasoline LOIs increased to ~6.2 pL on-column, while diesel could not be correctly identified at the concentrations tested. For the neat dilutions, GC-TOF generally provided 2 better sensitivity over GC-MSD, while GC GC-TOF generally resulted in 10 better sensitivity over GC-MSD. In the presence of pyrolysate, GC-TOF was generally equivalent to GC-MSD, while GC GC-TOF continued to show 10 greater sensitivity relative to GC-MSD. Our findings demonstrate the superior sensitivity of GC GC-TOF and provide an important approach for interlaboratory benchmarking of modern instrumental performance in fire debris analysis

Placental DAPK1 and autophagy marker LC3B-II are dysregulated by TNF-α in a gestational age-dependent manner

Autophagy, a cell-survival process responsible for degradation of protein aggregates and damaged organelles, is increasingly recognized as another mechanism essential for human placentation. A substantial body of experiments suggests inflammation and oxidative stress as the underlying stimuli for altered placental autophagy, giving rise to placenta dysfunction and pregnancy pathologies. Here, the hypothesis is tested whether or not pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-{alpha} are able to influence the expression profile of autophagy genes in human first-trimester villous placenta. Autophagy-focused qPCR arrays identified substantial downregulation of death-associated protein kinase 1 (DAPK1) in first-trimester placental explants in response to IL-6 and TNF-{alpha}, respectively. Immunohistochemistry of placental explants detected considerable DAPK1 staining in placental macrophages, villous cytotrophoblasts and less intense in the syncytiotrophoblast. Both immunohistochemistry and Western blot showed decreased DAPK1 protein in TNF-{alpha}-treated placental explants compared to control. On cellular level, DAPK1 expression decreased in SGHPL-4 trophoblasts in response to TNF-{alpha}. Observed changes in the expression profile of autophagy-related genes were reflected by significantly decreased lipidation of autophagy marker microtubule-associated protein light chain 3 beta (LC3B-II) in first trimester placental explants in response to TNF-{alpha}. Analysis of TNF-{alpha}-treated term placental explants showed decreased DAPK1 protein, whereas in contrast to first-trimester LC3B expression and lipidation increased. Immunohistochemistry of placental tissues from early-onset preeclampsia (PE) showed less DAPK1 staining, when compared to controls. Accordingly, DAPK1 mRNA and protein were decreased in primary trophoblasts isolated from early-onset PE, while LC3B-I and -II were increased. Results from this study suggest that DAPK1, a regulator of apoptosis, autophagy and programmed necrosis, decreases in human placenta in response to elevated maternal TNF-{alpha}, irrespective of gestational age. In contrast, TNF-{alpha} differentially regulates levels of autophagy marker LC3B in human placenta over gestation

A comment on the PCAST report:skip the “match”/“non-match” stage

This letter comments on the report “Forensic science in criminal courts: Ensuring scientific validity of feature-comparison methods” recently released by the President's Council of Advisors on Science and Technology (PCAST). The report advocates a procedure for evaluation of forensic evidence that is a two-stage procedure in which the first stage is “match”/“non-match” and the second stage is empirical assessment of sensitivity (correct acceptance) and false alarm (false acceptance) rates. Almost always, quantitative data from feature-comparison methods are continuously-valued and have within-source variability. We explain why a two-stage procedure is not appropriate for this type of data, and recommend use of statistical procedures which are appropriate

Analysis of post-explosion samples for forensic purposes : model field experiments

Celem badań było określenie powtarzalności wyników detonacji, zarówno pod względem ilości materiału pozostałego wybuchowego, jak i jego rozmieszczenia. Przeprowadzono modelowe eksperymenty na poligonie, polegające na detonacji ładunków pięciu różnych materiałów wybuchowych: TNT, RDX, PETN, dynamitu i materiału plastycznego, zawierającego RDX i TNT (kompozycja B). Każdy z eksperymentów (detonacja ładunku określonego materiału) powtórzono 3 razy. Eksperymenty prowadzono w kontrolowanych i powtarzalnych warunkach. Aby w sposób powtarzalny uzyskać próbki powybuchowe, w określonej odległości od detonowanych ładunków ustawiano arkusze ocynkowanej blachy. Po detonacji pobierano próbki, przecierając powierzchnię blach watą bawełnianą zwilżoną acetonem. Następnie próbki ekstrahowano dwiema porcjami metanolu, z użyciem łaźni ultradźwiękowej. Uzyskane ekstrakty łączono, zatężano przez odparowanie rozpuszczalnika, oczyszczano z cząstek stałych przez wirowanie i analizowano przy pomocy chromatografu cieczowego z detektorem typu DAD (HPLC-DAD). Chociaż eksperymenty powtarzano w taki sam sposób (na tyle na ile to możliwe w warunkach polowych) dla żadnego z pięciu badanych materiałów wybuchowych nie uzyskano powtarzalnych wyników, co można wytłumaczyć różnicami w efektywności detonacji, które najwyraźniej mogą wystąpić nawet dla pozornie identycznych ładunków. Nie zaobserwowano również spodziewanej zależności pomiędzy odległością od ładunku a ilością materiału w próbkach pobranych po wybuchu. Można to wytłumaczyć tym, że cząsteczki nieprzereagowanego materiału wybuchowego podczas wybuchu nie są rozpraszane równomiernie.The aim of research was to check the repeatability of explosion both for amount and distribution of explosives residues. The model field experiments were conducted. Charges of five different explosives: TNT, RDX, PETN, dynamite, and Composition B were detonated. Each experiment (detonation of the charge of each specific explosive) was repeated three times. The experiments were conducted under controlled conditions, exceeding those of research published so far. For each experiments three witness plates (sheets of galvanized steel) situated in a different distance from the charge were used, to collect post-blast residues in a reproducible way. Samples were collected by systematic swabbing of the surface of the plates by acetone moistened cotton swabs. Swabs were extracted with two portions of methanol, using ultrasonic bath. Extracts were combined, concentrated by solvent evaporation, cleaned by centrifugation, and analysed using HPLC-DAD. Although each of the experiments were conducted in a repeatable and uniform fashion (as much as possible in field conditions), the results proved to be unrepeatable for each of the five explosives tested. This lack of reproducibility may be explained by differences in the efficiency of a detonation which can, apparently, occur even for seemingly identical charges. Also, the intuitively expected relationship between distance from the charge and the amount of postblast residues was not observed. This may be explained by the fact that during detonation particles of unreacted explosives are not uniformly dispersed in all directions

Assigning moral roles within the Second World War in Europe: National similarities, differences, and implications for group-level moral representations

The moral roles assigned to nations that took part in the Second World War cast a shadow over contemporary international politics. To understand contemporary moral beliefs about the war, we took 11 mostly student samples from 9 nations that took part in the European theater of war (total N = 1,427). We asked respondents, in free and scaled listings, to identify the war’s heroes, villains, victims, and recipients of help. Nations and individuals seen as heroes, victims and villains could be readily identified by most samples and showed both continuity and difference across nations. Most nations preferentially assigned themselves hero and victim roles, and the two were correlated positively, showing ingroup favoritism linked to victimhood. These findings show the importance of morality to contemporary views of the war and suggest further directions for studying today’s political climate in Europe and elsewhere

ENFSI guideline for evaluative reporting in forensic science

Criminal Justice: Legitimacy, accountability, and effectivit